Genetic diversity and resistance to Fusarium head blight in synthetic hexaploid wheat derived from Aegilops tauschii and diverse Triticum turgidum subspecies

Authors: SZABO-HEVER, AGNES - North Dakota State University; ZHANG, QIJUN - North Dakota State University; Friesen, Timothy; SHAOBIN, ZHONG - North Dakota State University; ELIAS, ELIAS - North Dakota State University; CAI, XIWEN - North Dakota State University; Jin, Yue; Faris, Justin; Chao, Shiaoman; Xu, Steven

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2018
Publication Date: 12/11/2018
Citation: Szabo-Hever, A., Zhang, Q., Friesen, T.L., Shaobin, Z., Elias, E.M., Cai, X., Jin, Y., Faris, J.D., Chao, S., Xu, S.S. 2018. Genetic diversity and resistance to Fusarium head blight in synthetic hexaploid wheat derived from Aegilops tauschii and diverse Triticum turgidum subspecies. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2018.01829.
DOI: https://doi.org/10.3389/fpls.2018.01829

Interpretive Summary: Bread wheat and synthetic wheat both have three closely related genomes A, B, and D derived from hybridization between the wheat progenitor species carrying A and B genomes and a goatgrass species (Aegilops tauschii) with the D genome. Compared to bread wheat which originated about 8,000 years ago from natural hybridization, synthetic wheat has been developed by breeders as a recreation of bread wheat. To introduce useful genes into modern wheat from its AB- and/or D-genome ancestors, we recently developed 200 new synthetic wheat lines. In this study, we evaluated 149 of the synthetic wheat lines and their 74 AB-genome wheat parents for resistance to scab, a fungal disease that is currently devastating wheat crops in the U.S. and many other wheat-growing regions globally. The evaluation shows that scab resistance of the synthetic lines varied greatly depending on their Ae. tauschii and AB-genome wheat parents. As expected, most of the synthetic lines were more resistant than their AB-genome wheat parents, indicating that the D genome may play a major role in reducing disease infection in the synthetic lines. Thirteen synthetic lines consistently showed a high level of scab resistance across different environments and they may represent a new source of scab resistance that breeders can use for further wheat improvement.

Technical Abstract: Synthetic hexaploid wheat (SHW) can serve as a bridge for the transfer of useful genes from Aegilops tauschii and tetraploid wheat (Triticum turgidum) into common wheat (T. aestivum). The objective of this study was to evaluate 149 SHW lines and their 74 tetraploid parents for their genetic diversity, breeding values and inter-genomic interactions for resistance to Fusarium head blight (FHB). The genetic diversity analysis was performed based on the population structure established using 4,674 and 3,330 polymorphic SNP markers among the SHW lines and tetraploid parents, respectively. The results showed that all T. carthlicum and most T. dicoccum accessions formed different clusters and subpopulations, respectively, whereas all the T. durum, T. polonicum, T. turgidum, and T. turanicum accessions were clustered together, suggesting that T. durum was more closely related to T. polonicum, T. turgidum, and T. turanicum than to T. dicoccum. The genetic diversity of the SHW lines mainly reflected that of the tetraploid parents. The SHW lines and their tetraploid parents were evaluated for reactions to FHB in two greenhouse seasons and at two field nurseries for two years. As expected, most of the SHW lines were more resistant than their tetraploid parents in all environments. The FHB severities of the SHW lines varied greatly depending on the Ae. tauschii and tetraploid genotypes involved. Most of the SHW lines with a high level of FHB resistance were generally derived from the tetraploid accessions with a high level of FHB resistance. Among the 149 SHW lines, 140 were developed by using three Ae. tauschii accessions CIae 26, PI 268210, and RL 5286. These SHW lines showed FHB severities reduced by 21.7%, 17.3%, and 11.5%, respectively, with an average reduction of 18.3%, as compared to the tetraploid parents, suggesting that the D genome may play a major role in reducing disease severity in the SHW lines. Thirteen SHW lines consistently showed a high level of FHB resistance compared to the resistant check, Sumai 3, in each environment. These SHW lines will be useful for the development of FHB-resistant wheat germplasm and populations for discovery of novel FHB resistance genes.